arXiv subjects

Luís F. Seoane

Publications and source records attributed to Luís F. Seoane.

10 recordsLinked to original sources

arXiv2019

Aging, computation, and the evolution of neural regeneration processes

Metazoans are capable of gathering information from their environments and respond in predictable ways. These computational tasks are achieved by means of more or less complex networks of neurons. Task performance must be reliable over an individual's lifetime and must deal robustly with the finite lifespan of cells or with connection failure - rendering aging a relevant feature in this context. How do computations degrade over an organism's lifespan? How reliable can computations remain throughout? In order to answer these questions, here we approach the problem under a multiobjective (Pareto) optimization approach. We consider a population of digital organisms equipped with a neural network that must solve a given computational task reliably. We demand that they remain functional (as reliable as possible) for an extended lifespan. Neural connections are costly (as an associated metabolism in living beings) and degrade over time. They can also be regenerated at some expense. We investigate the simultaneous minimization of the metabolic burden (due to connections and regeneration costs) and the computational error and the tradeoffs emerging thereof. We show that Pareto optimal designs display a broad range of potential solutions: from small networks with high regeneration rate, to larger and redundant circuits that regenerate slowly. The organism's lifespan and the external damage rates are found to act as an evolutionary pressure that improve the exploration of the space of solutions and poses tighter optimality conditions. We also find that large damage rates to the circuits can constrain the space of the possible and pose organisms to commit to unique strategies for neural systems maintenance.

q-bio.NC↗

arXiv2018

Is the coexistence of Catalan and Spanish possible in Catalonia?

We study the stability of two coexisting languages (Catalan and Spanish) in Catalonia (North-Eastern Spain), a key European region in political and economic terms. Our analysis relies on recent, abundant empirical data that is studied within an analytic model of population dynamics. This model contemplates the possibilities of long-term language coexistence or extinction. We establish that the most likely scenario is a sustained coexistence. The data needs to be interpreted under different circumstances, some of them leading to the asymptotic extinction of one of the languages involved. We delimit the cases in which this can happen. Asymptotic behavior is often unrealistic as a predictor for complex social systems, hence we make an attempt at forecasting trends of speakers towards $2030$. These also suggest sustained coexistence between both tongues, but some counterintuitive dynamics are unveiled for extreme cases in which Catalan would be likely to lose an important fraction of speakers. As an intermediate step, model parameters are obtained that convey relevant information about the prestige and interlinguistic similarity of the tongues as perceived by the population. This is the first time that these parameters are quantified rigorously for this couple of languages. Remarkably, Spanish is found to have a larger prestige specially in areas which historically had larger communities of Catalan monolingual speakers. Limited, spatially-segregated data allows us to examine more fine grained dynamics, thus better addressing the likely coexistence or extinction. Variation of the model parameters across regions are informative about how the two languages are perceived in more urban or rural environments.

physics.soc-ph↗

arXiv2015

A multiobjective optimization approach to statistical mechanics

Optimization problems have been the subject of statistical physics approximations. A specially relevant and general scenario is provided by optimization methods considering tradeoffs between cost and efficiency, where optimal solutions involve a compromise between both. The theory of Pareto (or multi objective) optimization provides a general framework to explore these problems and find the space of possible solutions compatible with the underlying tradeoffs, known as the {\em Pareto front}. Conflicts between constraints can lead to complex landscapes of Pareto optimal solutions with interesting implications in economy, engineering, or evolutionary biology. Despite their disparate nature, here we show how the structure of the Pareto front uncovers profound universal features that can be understood in the context of thermodynamics. In particular, our study reveals that different fronts are connected to different classes of phase transitions, which we can define robustly, along with critical points and thermodynamic potentials. These equivalences are illustrated with classic thermodynamic examples.

cond-mat.stat-mech↗

arXiv2015

Multiobjective Optimization and Phase Transitions

Many complex systems obey to optimality conditions that are usually not simple. Conflicting traits often interact making a Multi Objective Optimization (MOO) approach necessary. Recent MOO research on complex systems report about the Pareto front (optimal designs implementing the best trade-off) in a qualitative manner. Meanwhile, research on traditional Simple Objective Optimization (SOO) often finds phase transitions and critical points. We summarize a robust framework that accounts for phase transitions located through SOO techniques and indicates what MOO features resolutely lead to phase transitions. These appear determined by the shape of the Pareto front, which at the same time is deeply related to the thermodynamic Gibbs surface. Indeed, thermodynamics can be written as an MOO from where its phase transitions can be parsimoniously derived; suggesting that the similarities between transitions in MOO-SOO and Statistical Mechanics go beyond mere coincidence.

physics.soc-ph↗

arXiv2015

Images from the Mind: BCI image evolution based on Rapid Serial Visual Presentation of polygon primitives

This paper provides a proof of concept for an EEG-based reconstruction of a visual image which is on a user's mind. Our approach is based on the Rapid Serial Visual Presentation (RSVP) of polygon primitives and Brain-Computer Interface (BCI) technology. The presentation of polygons that contribute to build a target image (because they match the shape and/or color of the target) trigger attention-related EEG patterns. Accordingly, these target primitives can be determined using BCI classification of Event-Related Potentials (ERPs). They are then accumulated in the display until a satisfactory reconstruction is reached. Selection steps have an average classification accuracy of $75\%$. $25\%$ of the images could be reconstructed completely, while more than $65\%$ of the available visual details could be captured on average. Most of the misclassifications were not misinterpretations of the BCI concerning users' intent; rather, users tried to select polygons that were different than what was intended by the experimenters. Open problems and alternatives to develop a practical BCI-based image reconstruction application are discussed.

q-bio.NC↗

arXiv2014

Ambiguity in language networks

Human language defines the most complex outcomes of evolution. The emergence of such an elaborated form of communication allowed humans to create extremely structured societies and manage symbols at different levels including, among others, semantics. All linguistic levels have to deal with an astronomic combinatorial potential that stems from the recursive nature of languages. This recursiveness is indeed a key defining trait. However, not all words are equally combined nor frequent. In breaking the symmetry between less and more often used and between less and more meaning-bearing units, universal scaling laws arise. Such laws, common to all human languages, appear on different stages from word inventories to networks of interacting words. Among these seemingly universal traits exhibited by language networks, ambiguity appears to be a specially relevant component. Ambiguity is avoided in most computational approaches to language processing, and yet it seems to be a crucial element of language architecture. Here we review the evidence both from language network architecture and from theoretical reasonings based on a least effort argument. Ambiguity is shown to play an essential role in providing a source of language efficiency, and is likely to be an inevitable byproduct of network growth.

physics.soc-ph↗

arXiv2013

Synthetic biocomputation design using supervised gene regulatory networks

The potential of synthetic biology techniques for designing complex cellular circuits able to solve complicated computations opens a whole domain of exploration, beyond experiments and theory. Such cellular circuits could be used to carry out hard tasks involving decision-making, storage of information, or signal processing. Since Gene Regulatory Networks (GRNs) are the best known technical approach to synthetic designs, it would be desirable to know in advance the potential of such circuits in performing tasks and how classical approximations dealing with neural networks can be translated into GRNs. In this paper such a potential is analyzed. Here we show that feed-forward GRNs are capable of performing classic machine intelligence tasks. Therefore, two important milestones in the success of Artificial Neural Networks are reached for models of GRNs based on Hill equations, namely the back-propagation algorithm and the proof that GRNs can approximate arbitrary positive functions. Potential extensions and implications for synthetic designs are outlined.

q-bio.NC↗

arXiv2013

Analytic solution of a model of language competition with bilingualism and interlinguistic similarity

An in-depth analytic study of a model of language dynamics is presented: a model which tackles the problem of the coexistence of two languages within a closed community of speakers taking into account bilingualism and incorporating a parameter to measure the distance between languages. After previous numerical simulations, the model yielded that coexistence might lead to survival of both languages within monolingual speakers along with a bilingual community or to extinction of the weakest tongue depending on different parameters. In this paper, such study is closed with thorough analytical calculations to settle the results in a robust way and previous results are refined with some modifications. From the present analysis it is possible to almost completely assay the number and nature of the equilibrium points of the model, which depend on its parameters, as well as to build a phase space based on them. Also, we obtain conclusions on the way the languages evolve with time. Our rigorous considerations also suggest ways to further improve the model and facilitate the comparison of its consequences with those from other approaches or with real data.

physics.soc-ph↗

arXiv2012

Successful attack on permutation-parity-machine-based neural cryptography

An algorithm is presented which implements a probabilistic attack on the key-exchange protocol based on permutation parity machines. Instead of imitating the synchronization of the communicating partners, the strategy consists of a Monte Carlo method to sample the space of possible weights during inner rounds and an analytic approach to convey the extracted information from one outer round to the next one. The results show that the protocol under attack fails to synchronize faster than an eavesdropper using this algorithm.

cs.CR↗

arXiv2011

Importance of interlinguistic similarity and stable bilingualism when two languages compete

In order to analyze the dynamics of two languages in competition, one approach is to fit historical data on their numbers of speakers with a mathematical model in which the parameters are interpreted as the similarity between those languages and their relative status. Within this approach, we show here, on the basis of a detailed analysis and extensive calculations, the outcomes that can emerge for given values of these parameters. Contrary to previous results, it is possible that in the long term both languages coexist and survive. This happens only when there is a stable bilingual group, and this is possible only if the competing languages are sufficiently similar, in which case its occurrence is favoured by both similarity and status symmetry.

physics.soc-ph↗